code: def Datapath(self, request_iterator, context):
      start_time = time.time()
      # set to True if client shuts down gracefully
      cleanup_requested = False
      metadata = {k: v for k, v in context.invocation_metadata()}
      client_id = metadata.get("client_id")
      if client_id is None:
          logger.error("Client connecting with no client_id")
          return
      logger.debug(f"New data connection from client {client_id}: ")
      accepted_connection = self._init(client_id, context, start_time)
      response_cache = self.response_caches[client_id]
      # Set to False if client requests a reconnect grace period of 0
      reconnect_enabled = True
      if not accepted_connection:
          return
      try:
          request_queue = Queue()
          queue_filler_thread = Thread(
              target=fill_queue,
              daemon=True,
              args=(request_iterator, request_queue),
          )
          queue_filler_thread.start()
          """For non `async get` requests, this loop yields immediately
              For `async get` requests, this loop:
                   1) does not yield, it just continues
                   2) When the result is ready, it yields
              """
          for req in iter(request_queue.get, None):
              if isinstance(req, ray_client_pb2.DataResponse):
                  # Early shortcut if this is the result of an async get.
                  yield req
                  continue
  
              assert isinstance(req, ray_client_pb2.DataRequest)
              if _should_cache(req) and reconnect_enabled:
                  cached_resp = response_cache.check_cache(req.req_id)
                  if isinstance(cached_resp, Exception):
                      # Cache state is invalid, raise exception
                      raise cached_resp
                  if cached_resp is not None:
                      yield cached_resp
                      continue
  
              resp = None
              req_type = req.WhichOneof("type")
              if req_type == "init":
                  resp_init = self.basic_service.Init(req.init)
                  resp = ray_client_pb2.DataResponse(
                      init=resp_init,
                  )
                  with self.clients_lock:
                      self.reconnect_grace_periods[
                          client_id
                      ] = req.init.reconnect_grace_period
                      if req.init.reconnect_grace_period == 0:
                          reconnect_enabled = False
  
              elif req_type == "get":
                  if req.get.asynchronous:
                      get_resp = self.basic_service._async_get_object(
                          req.get, client_id, req.req_id, request_queue
                      )
                      if get_resp is None:
                          # Skip sending a response for this request and
                          # continue to the next requst. The response for
                          # this request will be sent when the object is
                          # ready.
                          continue
                  else:
                      get_resp = self.basic_service._get_object(
                          req.get, client_id
                      )
                  resp = ray_client_pb2.DataResponse(get=get_resp)
              elif req_type == "put":
                  if not self.put_request_chunk_collector.add_chunk(
                      req, req.put
                  ):
                      # Put request still in progress
                      continue
                  put_resp = self.basic_service._put_object(
                      self.put_request_chunk_collector.data,
                      req.put.client_ref_id,
                      client_id,
                      req.put.owner_id,
                  )
                  self.put_request_chunk_collector.reset()
                  resp = ray_client_pb2.DataResponse(put=put_resp)
              elif req_type == "release":
                  released = []
                  for rel_id in req.release.ids:
                      rel = self.basic_service.release(
                          client_id, rel_id
                      )
                      released.append(rel)
                  resp = ray_client_pb2.DataResponse(
                      release=ray_client_pb2.ReleaseResponse(
                          ok=released
                      )
                  )
              elif req_type == "connection_info":
                  resp = ray_client_pb2.DataResponse(
                      connection_info=self._build_connection_response()
                  )
              elif req_type == "prep_runtime_env":
                  with self.clients_lock:
                      resp_prep = self.basic_service.PrepRuntimeEnv(
                          req.prep_runtime_env
                      )
                      resp = ray_client_pb2.DataResponse(
                          prep_runtime_env=resp_prep
                      )
              elif req_type == "connection_cleanup":
                  cleanup_requested = True
                  cleanup_resp = (
                      ray_client_pb2.ConnectionCleanupResponse()
                  )
                  resp = ray_client_pb2.DataResponse(
                      connection_cleanup=cleanup_resp
                  )
              elif req_type == "acknowledge":
                  # Clean up acknowledged cache entries
                  response_cache.cleanup(req.acknowledge.req_id)
                  continue
              elif req_type == "task":
                  with self.clients_lock:
                      task = req.task
                      if not self.client_task_chunk_collector.add_chunk(
                          req, task
                      ):
                          # Not all serialized arguments have arrived
                          continue
                      arglist, kwargs = loads_from_client(
                          self.client_task_chunk_collector.data,
                          self.basic_service,
                      )
                      self.client_task_chunk_collector.reset()
                      resp_ticket = self.basic_service.Schedule(
                          req.task, arglist, kwargs, context
                      )
                      resp = ray_client_pb2.DataResponse(
                          task_ticket=resp_ticket
                      )
              elif req_type == "terminate":
                  with self.clients_lock:
                      response = self.basic_service.Terminate(
                          req.terminate, context
                      )
                      resp = ray_client_pb2.DataResponse(
                          terminate=response
                      )
              elif req_type == "list_named_actors":
                  with self.clients_lock:
                      response = self.basic_service.ListNamedActors(
                          req.list_named_actors
                      )
                      resp = ray_client_pb2.DataResponse(
                          list_named_actors=response
                      )
              else:
                  raise Exception(
                      f"Unreachable code: Request type "
                      f"{req_type} not handled in Datapath"
                  )
              resp.req_id = req.req_id
              if _should_cache(req) and reconnect_enabled:
                  response_cache.update_cache(req.req_id, resp)
              yield resp
      except Exception as e:
          logger.exception("Error in data channel:")
          recoverable = _propagate_error_in_context(e, context)
          invalid_cache = response_cache.invalidate(e)
          if not recoverable or invalid_cache:
              context.set_code(grpc.StatusCode.FAILED_PRECONDITION)
              # Connection isn't recoverable, skip cleanup
              cleanup_requested = True
      finally:
          logger.debug(f"Stream is broken with client {client_id}")
          queue_filler_thread.join(QUEUE_JOIN_SECONDS)
          if queue_filler_thread.is_alive():
              logger.error(
                  "Queue filler thread failed to join before timeout: {}".format(
                      QUEUE_JOIN_SECONDS
                  )
              )
          cleanup_delay = self.reconnect_grace_periods.get(client_id)
          if not cleanup_requested and cleanup_delay is not None:
              logger.debug(
                  "Cleanup wasn't requested, delaying cleanup by"
                  f"{cleanup_delay} seconds."
              )
              # Delay cleanup, since client may attempt a reconnect
              # Wait on the "stopped" event in case the grpc server is
              # stopped and we can clean up earlier.
              self.stopped.wait(timeout=cleanup_delay)
          else:
              logger.debug(
                  "Cleanup was requested, cleaning up immediately."
              )
          with self.clients_lock:
              if client_id not in self.client_last_seen:
                  logger.debug("Connection already cleaned up.")
                  # Some other connection has already cleaned up this
                  # this client's session. This can happen if the client
                  # reconnects and then gracefully shut's down immediately.
                  return
              last_seen = self.client_last_seen[client_id]
              if last_seen > start_time:
                  # The client successfully reconnected and updated
                  # last seen some time during the grace period
                  logger.debug("Client reconnected, skipping cleanup")
                  return
              # Either the client shut down gracefully, or the client
              # failed to reconnect within the grace period. Clean up
              # the connection.
              self.basic_service.release_all(client_id)
              del self.client_last_seen[client_id]
              if client_id in self.reconnect_grace_periods:
                  del self.reconnect_grace_periods[client_id]
              if client_id in self.response_caches:
                  del self.response_caches[client_id]
              self.num_clients -= 1
              logger.debug(
                  f"Removed client {client_id}, "
                  f"remaining={self.num_clients}"
              )
  
              # It's important to keep the Ray shutdown
              # within this locked context or else Ray could hang.
              # NOTE: it is strange to start ray in server.py but shut it
              # down here. Consider consolidating ray lifetime management.
              with disable_client_hook():
                  if self.num_clients == 0:
                      logger.debug("Shutting down ray.")
                      ray.shutdown()
  
imports: from collections import defaultdict
  from ray.util.client.server.server_pickler import loads_from_client
  import ray
  import logging
  import grpc
  from queue import Queue
  import sys
  from typing import Any, Dict, Iterator, TYPE_CHECKING, Union
  from threading import Event, Lock, Thread
  import time
  import ray.core.generated.ray_client_pb2
  import ray.core.generated.ray_client_pb2_grpc
  from ray.util.client.common import CLIENT_SERVER_MAX_THREADS, _propagate_error_in_context, OrderedResponseCache
  from ray.util.client import CURRENT_PROTOCOL_VERSION
  from ray.util.debug import log_once
  from ray._private.client_mode_hook import disable_client_hook
label_desc: Use image node_id 2 for calling the DataServicer obj's underlying member method code with example usage: obj.Datapath(request_iterator, context) without return types